So, I was doing some stuff on a custom joomla component and I wanted to use bootstrap.
Here's the issue:

As soon as bootstrap css is loaded a few things in the joomla admin interface break.

Namely the icons of the buttons on the top right (new, save, etc...) and modal buttons which suddenly appeared elsewhere and with a different form.

A quick search turned up this thread:

https://ux.joomla.org/forum/User-Research/662-Bootstrap-and-Joomla-156725---a-common-solution-needed

Here's the essence of it.

In bootstrap.css (or equivalent) do the following:

1. rename all occurences of
   
   .modal
   
   to
   
   div.modal


2. rename all occurences of
   
   [class^="icon-"]
   
   to
   
   i[class^="icon-"]